A baby’s first words may seem spur of the moment, but really, the little ones have practiced their “Mamas” and “Dadas” for months in their minds.

Using what looks like a hair dryer from Mars, researchers from the University of Washington have taken the most precise peeks yet into the fireworks display of neural activity that occurs when infants listen to people speak.

They found that the motor area of the brain, which we use to produce speech, is very active in babies 7 to 12 months old when they listen to speech components.

“What we’re seeing is that the babies are practicing because they want to talk back,” says Patricia Kuhl, a speech psychologist at the University of Washington and the lead author on the paper, published Monday in the Proceedings of the National Academies of Sciences.

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They found that the motor part of the brain lit up when the baby listened to the sounds, indicating that they were trying to mimic or respond to the speech. By 12 months, the babies, who had English-speaking parents, had a harder time responding to the Spanish-language sounds.

Susan Goldin-Meadow, a developmental psychologist from the University of Chicago who was not involved in the study, says it furthers understanding of how babies process language. “We’ve had the behavioral data for a while,” she says. “But this provides evidence on the neural level.”

Kuhl says that her research supports parent’s use of “parentese,” or baby speak, a form of talking to babies with a higher pitch, slower pace and exaggerated facial expressions. “This is a good way to promote their itty-bitty social skills to develop,” she says.